Reports pertinent to bacterial arthritis in 1997 included two large, multi-year surveys of joint infection in patients from defined European health districts, noting trends including the declining incidence of gonococcal arthritis and an increasing number of prosthetic joint infections. Children with infected joints generally fare better than adults despite having proportionately more infections due to gram-negative organisms, of which Hemophilus influenzae comprises an ever smaller portion as the fastidious Kingella kingea is emerging. Joint infections remain an uncommon complication of immunodeficiency due to HIV, with responsible agents, affected sites, and clinical course also influenced by certain HIV comorbidities such as intravenous drug user and hemophilia. The rare immunodeficient patient with hypogammaglobulinemia retains a nearly unique susceptibility to joint infection with mycoplasmas, which can cause considerable morbidity if not promptly recognized and treated. Polymerase chain reaction can detect remnants of bacteria in the face of negative conventional cultures, but inoculation of synovial fluid into blood cultures bottles may be a more immediate and practical method to increase the yield in suspected septic arthritis.